1. Technical Field
This invention relates generally to a method and apparatus for detecting the presence of blood in an aqueous solution. More specifically, the present invention relates to a method and apparatus in which a dry reagent and dry peroxygen compound are packaged in a test pad for in-home testing of fecal material or urine in a toilet bowl.
2. Prior Art
Early detection of gastrointestinal cancers is vital to successful treatment. One sign of gastrointestinal cancer is the presence of blood in fecal material or urine. Frequently when blood is visible the cancer has already progressed to a late stage. Tests for detecting blood in such samples before it is visible are very useful but have suffered from certain problems and deficiencies.
U.S. Pat. No. 2,838,377 to Fonner discloses one method for detecting the presence of occult, unseen, blood in feces and urine. In Fonner, an envelope of sheet material contains a dried reagent material that is adapted to be dropped into a toilet bowl containing water and either feces, urine or both with the reagent changing color if blood is present in the solution. The reagent mixtures are selected from the group consisting of o-tolidine, benzidine, or o-toluidine. The primary disadvantage of the Fonner test is that the reagents used are either suspected or known carcinogens. Another problem with the Fonner test is its lack of specificity causing it to frequently yield a positive test result when no blood is actually present in the sample.
U.S. Pat. No. 3,996,006 to Pagano discloses a specimen test slide comprising of a multi-fold cardboard package having a sheet of test paper impregnated with a guaiac based reagent material enclosed therein. The test is performed by applying samples of feces on one side of the test paper after opening a flap formed in the test slide and sending the test slide to a laboratory for analysis. Laboratory analysis is performed by applying a peroxide solution to the opposite side of the test paper and observing the test paper to determine whether a color reaction caused by the presence of blood occurs. The necessity of handling fecal material and sending the specimen to a laboratory for later analysis is a serious disadvantage of the Pagano test.
U.S. Pat. No. 4,175,923 to Friend discloses a method for determining the presence of occult blood in the bowl of a toilet by first spraying a developing solution of ethyl alcohol and hydrogen peroxide on a sheet of guaiac impregnated test paper and then dropping the test paper into the bowl. One problem with Friend is that patients are reluctant to use liquid reagents. Also, the ethyl alcohol and hydrogen peroxide solution is caustic which may cause irritation if it comes into contact with a patient's skin. Even though the above problems are encountered when an activating solution of hydrogen peroxide is applied to a test pad, Friend teaches that such a solution is essential for a test using a guaiac reagent in a cold water environment.
Various other tests for the presence of occult blood in fecal material and urine samples have been proposed, however, none have realized the advantages of the present invention wherein a patient may conveniently test for the presence of occult blood in a toilet bowl without the use of carcinogenic materials and without the need for activating solutions.